Question

delta Go = -431.16kJ/mol - (298k X 0.12529 kJ/K*mol)

I am having trouble converting the units for delta H and delta s to match. I multiplied delta H by 1000 to get kJ but this didn't give me the correct answer.



Chemistry(Please help) - Dev, Wednesday, April 25, 2012 at 6:56pm
If your answer is in J then multiply -431.16 by thousand and you delta S .12529. Make sure all your unit are in J/mol K and Temperature in K.



Chemistry(Please help) - Nem, Wednesday, April 25, 2012 at 6:58pm
-468496.42 J



Chemistry(Please help) - DrBob222, Wednesday, April 25, 2012 at 10:02pm
delta H is usually listed in kJ/mol and S in units of J/mol. Most of the time I want to use dG I must convert it to J so I usually convert delta H to J (1000 x delta H in kJ/mol = delta H in J/mol) and that will match S in J/mol. That will give you dG in J/mol.




I did -431.16kJ/mol X 1000 = -431160

Then -431160 - (298 X 0.12529 kJ/K*mol) = -431197.33 for delta G but this answer was said to be incorrect, I do not know why??

Answer 1

Hannah, you converted BOTH. You don't do that. You convert one or the other, not both. Convert 431.16 kJ to J = 431,160 J and use S as 125.29 OR convert S of 125.29 J/mol to kJ = 0.12529.
So 431,160 - 298*125.29 = ? dG in J or
431.16 - 298*0.12529 = ? dG in kJ.
I go the dG in J route especially if I intend to use this to calculate K